Solid alkaline detergent compositions are widely used for household and industrial dishwashing, laundering clothing and general surface cleansing. The greater amount of such cleaning compositions consumed consists of solid granules, tablets or pellets and solid blocks. Solid compositions are advantageous for their improved handling and safety, elimination of component segregation during transportation and storage and increased concentration of active components within the composition. These detergent compositions typically incorporate a source of alkalinity such as an alkali metal hydroxide, carbonate, bicarbonate, silicate or mixtures thereof and a hardness sequestering agent or builder as their primary cleaning components. The hardness sequestering agent acts to condition the wash water by chelating or otherwise complexing the metal cations responsible for the precipitation of alkali metal builder salts and detergents. The alkaline components impart detergency to the compositions by breaking down acidic and proteinaceous soils.
Automatic warewashing detergents are well known. Historically, automatic warewashing detergents contain high amounts of caustic component, in particular sodium hydroxide. In recent years, attention has been directed to producing a highly effective detergent material from less caustic materials such as soda ash, also known as sodium carbonate, because of manufacturing, processing, etc. advantages. Consumers have also driven the push to formulate automatic warewashing detergents without caustic components.
Difficulty has ensued when attempting to formulate caustic-free warewashing detergents. This is due to at least one reason. Sodium carbonate is a mild base, and is substantially less strong than sodium hydroxide. Further on an equivalent molar basis, the pH of the sodium carbonate solution is one unit less than an equivalent solution of sodium hydroxide (an order of magnitude reduction in strength of alkalinity). Sodium carbonate formulations were not given serious consideration in the industry for use in heavy duty cleaning operations because of this difference in alkalinity. The industry believed carbonate could not adequately clean under the demanding conditions of time, soil load and type and temperature found in the institutional and industrial cleaning market. A few sodium carbonate based formulations have been manufactured and sold in areas where cleaning efficiency is not paramount.
In recent times, certain industrial markets throughout the world have insisted upon caustic-free or substantially caustic-free warewashing detergents. In particular, customers in Japan have sought caustic-free warewashing detergents. In addition, customers have scrutinized chlorinated products and as a result there has been a movement to eliminate chlorine from warewashing detergents as well. While moving to an ash-based, substantially chlorine free detergent provides a more appealing product line; such a product must also maintain cleaning-ability. While manufacturers strive to meet customer's requests, the effectiveness of the product may be compromised when eliminating the caustic and chlorine components.
For the most part a caustic-free, chlorine-free warewashing detergent has been suitable except for removal of tenacious soils. Again, particularly in Japan where the consumption of fish is generally higher than in the Western markets, soils caused by the oil and protein of fish and generally caused by raw fish is a difficult soil to remove. The inventors have found that such fish soil is very tenacious and often resists removal by substantially caustic-free chlorine-free warewashing detergents. The Japanese customer has complained about the retention of such soil post-automatic warewashing of cooking and eating utensils and implements.
The present invention provides a solid composition that is substantially caustic-free and substantially chlorine free yet is effective at removing tenacious soils such as those caused by raw fish protein and oil. The present invention further provides a liquid detergent suitable for removing soils such as those caused by raw fish protein and oil.